首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7212篇
  免费   387篇
  国内免费   88篇
耳鼻咽喉   53篇
儿科学   188篇
妇产科学   163篇
基础医学   862篇
口腔科学   143篇
临床医学   527篇
内科学   1967篇
皮肤病学   218篇
神经病学   727篇
特种医学   275篇
外科学   1214篇
综合类   21篇
预防医学   307篇
眼科学   68篇
药学   386篇
中国医学   7篇
肿瘤学   561篇
  2023年   71篇
  2022年   59篇
  2021年   233篇
  2020年   140篇
  2019年   177篇
  2018年   214篇
  2017年   156篇
  2016年   206篇
  2015年   232篇
  2014年   289篇
  2013年   380篇
  2012年   548篇
  2011年   583篇
  2010年   330篇
  2009年   306篇
  2008年   472篇
  2007年   466篇
  2006年   469篇
  2005年   471篇
  2004年   428篇
  2003年   376篇
  2002年   314篇
  2001年   52篇
  2000年   44篇
  1999年   45篇
  1998年   46篇
  1997年   47篇
  1996年   28篇
  1995年   41篇
  1994年   37篇
  1993年   33篇
  1992年   23篇
  1991年   24篇
  1990年   28篇
  1989年   22篇
  1988年   25篇
  1987年   29篇
  1986年   24篇
  1985年   28篇
  1984年   22篇
  1983年   17篇
  1982年   15篇
  1981年   11篇
  1980年   9篇
  1979年   14篇
  1977年   6篇
  1976年   8篇
  1974年   10篇
  1969年   5篇
  1964年   6篇
排序方式: 共有7687条查询结果,搜索用时 31 毫秒
1.
BACKGROUND Surgery for gastric cancer is a complex procedure and lymphadenectomy is often mandatory.Postoperative mortality and morbidity after curative gastric cancer surgery is not insignificant.AIM To evaluate the factors determining mortality and morbidity in a population of patients undergoing R0 resection and D2 lymphadenectomy for gastric cancer.METHODS A retrospective analysis of clinical data and pathological characteristics(age,sex,primary site of the tumor,Lauren histotype,number of positive lymph nodes resected,number of negative lymph nodes resected,and depth of invasion as defined by the standard nomenclature)was conducted in patients with gastric cancer.For each patient we calculated the Kattan’s score.We arbitrarily divided the study population of patients into two groups based on the nomogram score(<100 points or≥100 points).Prespecified subgroups in these analyses were defined according to age(≤65 years or>65 years),and number of lymph nodes retrieved(≤35 lymph nodes or>35 lymph nodes).Uni-and multivariate analysis of clinical and pathological findings were performed to identify the factors affecting postoperative mortality and morbidity.RESULTS One-hundred and eighty-six patients underwent a curative R0 resection with D2 lymphadenectomy.Perioperative mortality rate was 3.8%(7 patients);a higher mortality rate was observed in patients aged>65 years(P=0.002)and in N+patients(P=0.04).Following univariate analysis,mortality was related to a Kattan’s score≥100 points(P=0.04)and the presence of advanced gastric cancer(P=0.03).Morbidity rate was 21.0%(40 patients).Surgical complications were observed in 17 patients(9.1%).A higher incidence of morbidity was observed in patients where more than 35 lymph nodes were harvested(P=0.0005).CONCLUSION Mortality and morbidity rate are higher in N+and advanced gastric cancer patients.The removal of more than 35 lymph nodes does not lead to an increase in mortality.  相似文献   
2.
Metabolomics may reveal novel insights into the etiology of prostate cancer, for which few risk factors are established. We investigated the association between patterns in baseline plasma metabolite profile and subsequent prostate cancer risk, using data from 3,057 matched case–control sets from the European Prospective Investigation into Cancer and Nutrition (EPIC). We measured 119 metabolite concentrations in plasma samples, collected on average 9.4 years before diagnosis, by mass spectrometry (AbsoluteIDQ p180 Kit, Biocrates Life Sciences AG). Metabolite patterns were identified using treelet transform, a statistical method for identification of groups of correlated metabolites. Associations of metabolite patterns with prostate cancer risk (OR1SD) were estimated by conditional logistic regression. Supplementary analyses were conducted for metabolite patterns derived using principal component analysis and for individual metabolites. Men with metabolite profiles characterized by higher concentrations of either phosphatidylcholines or hydroxysphingomyelins (OR1SD = 0.77, 95% confidence interval 0.66–0.89), acylcarnitines C18:1 and C18:2, glutamate, ornithine and taurine (OR1SD = 0.72, 0.57–0.90), or lysophosphatidylcholines (OR1SD = 0.81, 0.69–0.95) had lower risk of advanced stage prostate cancer at diagnosis, with no evidence of heterogeneity by follow-up time. Similar associations were observed for the two former patterns with aggressive disease risk (the more aggressive subset of advanced stage), while the latter pattern was inversely related to risk of prostate cancer death (OR1SD = 0.77, 0.61–0.96). No associations were observed for prostate cancer overall or less aggressive tumor subtypes. In conclusion, metabolite patterns may be related to lower risk of more aggressive prostate tumors and prostate cancer death, and might be relevant to etiology of advanced stage prostate cancer.  相似文献   
3.

Introduction

In this retrospective study we have analyzed a consecutive series of patients affected by isolated radial head Mason III fractures and treated with bone resection or prosthesis.

Patients and methods

This study includes 24 patients affected by fractures mentioned above and treated between July 2009 and November 2015.15 patients (average age 48 y.o.) have been treated with prosthesis. The remaining 9 (average age 573) have been treated with a capitellectomy instead.From a clinical point of view, we have evaluated the patients according to main performance indicators such as range of motion, pain, instability and Mayo Elbow Performance Score as parameters.

Results

We have found similar results in both group, with an average MEPS value of 95 in the prosthesis group and 966 in the radial head resection group.The range of motion was similar too: between 1,3° and 1203° in the first group and between 4,4° and 120° in the second one. No significant complication has detected in any patient.

Discussion

According to most recent literature, it is not precisely defined how to treat isolated Mason III fractures, contrary to what is defined in more complex pattern, in which prosthesis are now evaluated as the best indication.Due to radial head limited contribution to elbow stability, in absence of other bony or ligamentous lesions both capitellectomy and prosthesis can be good treatment in this kind of fracture.

Conclusion

According to our experience and to the most recent literature, we recommend prosthesis in patient younger than 50 y.o., high demanding or manual worker, while in other cases we think that radial head resection can be the treatment of choice.  相似文献   
4.
In this article, we report a case of isolated podal osteochondroma from the prehistoric Hypogeum of Calaforno (Giarratana, Ragusa, Sicily). Although the phalanx exhibiting the benign tumoral mass comes from a context featuring several commingled remains, the very good state of preservation of this bone allowed us to perform a comprehensive study of the neoplasm by applying a multidisciplinary approach encompassing archeology, morphology, stereomicroscopy, and radiology. The results from this very ancient specimen have been assessed in the light of the available paleopathological literature and clinical implications currently encountered in modern patients.  相似文献   
5.
6.
7.
Adiposity increases estrogen receptor (ER)-positive postmenopausal breast cancer risk. While mechanisms underlying this relationship are uncertain, dysregulated sex-steroid hormone production and insulin signaling are likely pathways. Our aim was to quantify mediating effects of fasting insulin and free estradiol in the adiposity and ER-positive postmenopausal breast cancer association. We used data from a case–cohort study of sex hormones and insulin signaling nested within the Melbourne Collaborative Cohort Study. Eligible women, at baseline, were not diagnosed with cancer, were postmenopausal, did not use hormone therapy and had no history of diabetes or diabetes medication use. Women with ER-negative disease or breast cancer diagnosis within the first follow-up year were excluded. We analyzed the study as a cumulative sampling case–control study with 149 cases and 1,029 controls. Missing values for insulin and free estradiol were multiply imputed with chained equations. Interventional direct (IDE) and indirect (IIE) effects were estimated using regression-based multiple-mediator approach. For women with body mass index (BMI) >30 kg/m2 compared to women with BMI 18.5–25 kg/m2, the risk ratio (RR) of breast cancer was 1.75 (95% confidence interval [CI] 1.05–2.91). The estimated IDE (RR) not through the mediators was 1.03 (95% CI 0.43–2.48). Percentage mediated effect through free estradiol was 72% (IIE-RR 1.56; 95% CI 1.11–2.19). There was no evidence for an indirect effect through insulin (IIE-RR 1.12; 95% CI 0.68–1.84; 28% mediated). Our results suggest that circulating free estradiol plays an important mediating role in the adiposity–breast cancer relationship but does not explain all of the association.  相似文献   
8.
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号